Atropisomerism of the C-1-C '-1 axis of 2,2 ',8,8 '-unsubstituted 1,1 '-binaphthyl derivatives

The Suzuki coupling of optically active (S)-binaphthyl bromide 10 with (S)- binaphthyl boronic acid 11 produced a diastereomeric mixture of tetrahydrox yquaternaphthyls 4. The coupling products 4 as well as their derivatives 5- 7 can be considered as members of the family of 1,1 ' -binaphthyl-3,3 ' -di ols. The C-1-C ' -1 axis of all these compounds was found to have an unusua lly high rotational barrier. Generally, the barrier is higher for derivativ es having more bulky substituents at the 3 and 3 ' positions.